image-dired: Make thumbnail rotation commands obsolete

image-dired: Make thumbnail rotation commands obsolete

* lisp/image-dired.el (image-dired-cmd-rotate-thumbnail-program)
(image-dired-cmd-rotate-thumbnail-options)
(image-dired-rotate-thumbnail)
(image-dired-rotate-thumbnail-left)
(image-dired-rotate-thumbnail-right): Make obsolete in favor of
'image-dired-refresh-thumb' and 'image-rotate'.  It makes no sense to
have destructive thumbnail rotation commands now that Emacs can rotate
thumbnails in memory, and it is very fast to just generate a new one
reflecting the rotation of the original.
(image-dired-thumbnail-mode-map): Remove menu entries and key bindings
for above obsolete commands.  The rotate right keybinding had already
been made ineffective by the local keymap added by 'insert-image'.